hello
Following this conversation, you will find hereafter a photo of a BMW '71 farb und ausstattungmusterbuch" dedicated to customers.
Years before computer, you could choose color of your car ,placing charts under the transparent profile.
This gives us the opportunity of seeing an E9, half painted polaris metallic 60 and other half bristol 58.
The difference is all the more obvious, as one is metallic, and the other not.
And bristol is definitively gray........
...if this can help.